Compression riveter



Feb. 9, 1943.3.

H. R. FISCHER COMPRESSION RIVETER Filed Jan. 30. 1940 2 Sheets-Sheet l INVENTOR. Howard E flame/r MW ATTO'RNEY Feb. 9, 1943. H. R. FISCHER 2,310,625

COMPRESSION RIVETER Filed Jan. .30, 1940 2 Sheets-Sheet 2 INVENTQR flan 5rd 1e F/scben This invention relates generally to riveting and like machines and more particularly to means for controlling the application of motive power in such machines.

riveting unit of the compression or squeeze type wherein a rivet set is moved with great force towards a stationary die formed as an integral part sure of return air. of the unit. The rivet set is operated either directly or indirectly by a driving piston movable l tural details of the invention will be apparent from the following description when read incon-- through a compression and return stroke to comaccompanying drawings,

plete a rivet heading operation. The driving pisjunction with the ton is actuated by pressure fluid admitted, under wherein: valve control, first in a direction to move the piston through its compression stroke and then in unit embodying the mechanism of the present a direction to move the piston through its return invention;

The pressure fluid used in the present machine is compressed air and the invention is concerned principally with the means for controlling and directing the flow of air through the throttle lever being omitted;

Fig. 3 is a diagrammatic View of the riveting unit showing the throttle control mechanism in fully actuated position and the piston assembly at the end of its compression stroke; and

Fig. 4 is a diagrammatic View of the throttle control mechanism in partly actuated position, wherein air is admitted only to the return cham- Among the general objects of the invention are to increase the power, reduce air consumption, and speed up the operation of a machine of the class aforementioned.

In carrying out these objects certain novel structural features have been developed including a throttle control mechanism which operates unber. der the control of a manually operable lever and acts normally to prevent the flow of air to the mechanism of the present invention is a portable compression riveter which is light in weight and is adapted to be held or supported in the hands of the operator, when in use. Referring to Fig. ing piston through its compression stroke. In 1 i Will be seen that the principal s ppo ti another o erating position of the control lever air elements f the maehine are a der 5, n is admitted to the unit and is so directed as to move the piston through its return stroke. The driving piston is of the type having a piston rod on which is mounted a pair of piston heads one of which i movame within a compression Chem. c linder 5 and. is held in place by screws 6a (Fig. her and the other of which is movable within a return chamber having a smaller diameter than the compression chamber. In all qpgra ti ng pp sirernairiisaomitteu o..th..

directiomto .returnthe p s; "lidfi'as smfilmfTlieretiirn air is never directed to "exhaustf and during the compression stroke is forced back into the main air line. y e H A pa t cu y e H is s wn here merely by way of illustration since any one of a the motion of the piston assembly durin the plurality of dilferently formed yokes may be atcompression stroke, a passageway is formed in the piston rod whereby live air from the compression chamber is conducted to the return the work to be done. chamber, above the piston head therein, to baldriving piston in any direction. In one operating position of the control lever air is admitted to the unit and is so directed as to move the drivaatths In order that the return air will not impede PatentedE-ebi 9, 1943 2,310,625 COMPRESSION RIVETER Howard R. Fischer, Detroit, Mich assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application January 30, 1940, Serial No. 316,299

8 Claims. (01.121-38) UNITED STATES PATENT OFFICE ton head. During the return stroke, the compression chamber is connected to exhaust. The principle of establishing communication between the compression chamber and the return chamber The invention is shown herein as embodied in a 5 represents an important feature of the invention, and it will be evident that this principle may be used for other purposes than to balance the pres- Other objects, additional features, and struc- Fig. 1 is a view, chiefly in section, of a riveting Fig. 2 is a cross-sectional view taken substantially along the line 2-2 of Fig. 1, showing the throttle valve mechanism in normal position, the

The machine disclosed herein as embodying the adapter 6, associated with the cylinder, and a U- shaped bracket 1 secured to the adapter. A pair of guard plates 10 enclose the open sides of the bracket I. The adapter 6 fits into one end of the 2) extending into the wall of the cylinder. The adapter extends a short distance beyond the end of the cylinder 5 and is secured to the side walls (one shown) of the bracket 1 by a pair of tie rods 8 and, a bolt 9. The lower or closed end of the bracket 1 is formed with. a downwardly extending rib 20 to which is detachably secured a tached to the rib 20; the selection of a particular yoke being determined by the requirements of Each yoke, however, is formed with an anvil head in which is positioned ance the pressure of the return air below the pisa dolly or contact element l2 engageable by a rivet set l3 movable within a projecting portion M of the bracket 1. The rivet set 3 is urged upward, or away from the element I2, by a pair of springs |5 (one shown) tensioned between a pin l6 passed through the rivet set and a stud supported by one of the guide plates I0. The upper end of the rivet set |3 contacts a shoulder formed on a lever l8 pivotally mounted on a stub shaft |9 rigidly mounted between the side walls of the bracket 1. The outer end of the lever I8 is bifurcated to form a pair of arms |8a which support a roller 2|. The roller 2| is normally spaced slightly from the lower one of a pair of rollers 22 mounted on the tie rods 8, and a wedge 23 is arranged to enter between the rollers 2| and 22 and thereby force the lever |8 in a counter-clockwise direction to operate the rivet set l3. The wedge 23 is pivotally connected to the bifurcated lower end of a piston rod 24 which forms part of a piston assembly movable within the cylinder 5. The wedge projects through an opening 25 formed in the adapter 6 and the lower end thereof normally engages, and rests on, the roller 2|. The side of the wedge 23 that is adjacent the roller 2| is formed with two inclined surfaces 23a and 23b adapted to be placed successively in cooperative relation with the roller 2|. The inclined surface 23a is considerably steeper than surface 23b so that, as the piston assembly including rod 24 moves downward, the lever l8 and rivet set l3 are moved rapidly through the first part of their stroke and then more slowly as the rivet set approaches the contact element 2.

The construction and arrangement of the parts comprising the rivet set mechanism, as distinguished from the fluid pressure control means, is the subject of a divisional application, Serial No. 470,442, filed December 29, 1942.

The piston assembly comprises, in addition to the rod 24, a pair of piston heads 26 and 21 mounted on the rod 24 and movable through respective chambers 28 and 29 formed in the cylinder 5. The chamber 29 is of considerably less diameter than the chamber 28 and is formed in a reduced elongated portion of the cylinder, which portion may be used as a handle for the unit. The outer end of the chamber 29 is closed by a cap 3|, and a piston rod bushing 32 positioned in the inner end of the chamber 29 acts as a seal between the chambers 28 and 29.

The piston assembly comprising rod 24 and piston heads 26 and 21 is reciprocated through the cylinder 5 by pressure fluid in the form of compressed air. As shown in Fig. 3 a pair of passageways 33 and 34 are formed in the cylinder 5, the former opening into the chamber 28 at a point above the piston head 26 therein and the latter opening into the chamber 29 at a point below the piston head 21 therein. Compressed air is directed through the passageway 33 into the chamber 28 and acts upon the piston head 26 to force the piston assembly from its Fig. 1 position to its Fig. 3 position, which movement represents the compression stroke of the machine. Air is directed through passageway 34 into chamber 29 and acts upon the piston head 21 to move the piston assembly from its Fig. 3 position to its Fig. 1 position. which movement represents the return stroke of the machine.

The flow of air through the passageways 33 and 34 is controlled by a valve mechanism settable by a manually operable lever 35 to a plurality of operating positions. In the normal position of the lever 35 the passageways 33 and 34 are cut off from the source of pressure fluid and passageway 33 is connected to exhaust. In one operating position of the lever 35 both passa ways are connected to the source of pressure fluid and live air flows into the chambers 28 and 29. In another operating position of the lever 35 live air is permitted to flow only into the return chamber 29 while compression chamber 28 is connected to exhaust. As shown in Fig. 2 the valve mechanism is housed in a cylindrical bore 36 formed in the cylinder 5 adjacent the reduced elongated portion thereof. The bore 36 extends at right angles to the chambers 28 and 29 and screwed into the lower end of the bore is a nut 31 which supports an air inlet swivel 3 8. The swivel 38 is formed with a threaded opening 39 adapted to receive one end of a pressure fluid conducting hose (not shown) leading from a suitable source of compressed air. Also positioned within the bore 36 above the swivel 38 is a bushing 4| enclosing a valve 42 of the piston type. The valve 42 extends below the bushing 4| and is formed with a collar 43, near its lower end, adapted to engage the inside lower edge of the bushing 4|. A compression spring 44, placed between the collar 43 and an abutment formed within the swivel 38, urges the valve 42 upward and serves to maintain the collar 43 in contact with the bushing 4 In this position of the valve 42, which is its normal position, the passage of air between the valve and its bushing 4| is prevented. Normally, the pressure of spring 44 is supplemented by the unbalanced pressure of live air acting on the lower end of valve 42. The periphery of the valve 42 is formed with an annular groove 45 adjacent two sets of ports 46 and 4'! opening into respective grooves 48 and 49 formed in the bushing 4|. The groove 48 is in communication with a passageway 5| (Figs. 3 and 4) leading to exhaust, while the groove 49 is in communication with the passageway 33 leading to the compression chamber 28. In the normal position of the valve 42 (Fig. 2) the annular groove 45 therein uncovers both sets of ports 46 and 41 and so connects the compression chamber 28 to exhaust. It will be seen, however, that movement of the valve 42 downward to the position shown in Fig. 3 serves to close the exhaust ports 46 and places the lower end of the annular groove 45 below the bushing 4|. Live air within the swivel 38 is then free to flow into the groove 45, out the ports 41 and then to chamber 28 through bushing groove 49 and passageway 33. As the pressure within chamber 28 increases, the piston assembly comprising elements 24, 2B and 21 is driven through its compression stroke. Upon the return of the valve 42 to normal the supply of live air to the chamber 28 is cut ofi and communication between the chamber and the exhaust passageway 5| is re-established.

As shown in Fig. 3, the passageway 34, whereby air is conducted to the return chamber 29, communicates with an annular groove 52 formed in the bushing 4|, near its upper end. A set of ports 53 connect the groove 52 to the interior of the bushing 4 I, at a point above the valve 42. A 1ongitudinal opening or passage 54 extends throughout the length of the valve 42 and air is conducted from the swivel 38 through the passage 54 and then to the return chamber 29 by way of ports 53, groove 52 and passageway 34. The flow of air through these ports and passageways to the chamber 29 is controlled by a valve 55 positioned in the enlarged lower end of the passage 54 and movable to a seated or closedposition with rethe l spect to the reduced portion of the passage. The valve 55 is formed on the lower end of a plunger 56 which extends through the opening 54 and through a plug 51 which closes the upper end of the bushing 4|. As shown in Fig. l, the upper end of the plunger 56 underlies an offset portion of the lever 35 so that a downward movement of the lever serves to depress the plunger and unseat the valve 55. A light compression spring 58, psitioned between the lower end of the plunger 55 and a retainer 59 fitted into the lower end of the piston valve 42, urges the plunger 56 upward to maintain the valve 55 normally closed. Air from the swivel 38 is admitted to the passage 54 through ports or openings formed in the retainer 59 and the lower end of the valve 42. Secured to the plunger 55, at a point above the valve 42, is a collar 6| arranged to actuate the valve 42 upon depression of the plunger. The collar BI is perforated to permit the passage of air thereby in all positions of the plunger 56. In the normal position of the plunger 56 (Fig. 2) the collar BI is spaced slightly above the valve 42 so that the plunger may be depressed a distance sufiicient to unseat the valve 55 without actuating the valve 42. During its initial movement, and before it actuates the valve 42, plunger 56 balances the end p essure supplementing spring 44 by admitting live air through valve 42 from the lower to the upper end thereof.

In the operation of the machine the lever 35 may be moved immediately to the fully actuated position of Fig. 3 to operate both valves 42 and 55 and admit live air to both chambers 28 and 29. The greater pressure within chamber 28 forces the piston assembly through its compression stroke, or downward, to the position shown in Fig. 3. Upon completion of the compression stroke the lever 35 and valves 42 and 55 are permitted to return toward normal position under the action of springs 54 and 58 until they reach the position shown in Fig. 4. The valve 42 has returned to normal position at this time whereas the lever 35 and plunger 55. are still partly depressed and the valve 55 is still open. Under this condition of operation, therefore, the chamber 28 is connected to exhaust and air is admitted to the chamber 29 to return the piston assembly. By reason of the constant pressure maintained in the return chamber 29, below the piston head 21, the return stroke begins as soon as the exhaust ports 46 are opened. At the end of the return stroke the lever 35 may be completely released and the flow of air through the unit in any direction will be prevented.

It will be noted that in both operating positions of the lever 35 air is admitted to the chamber 29 in a direction to return the piston assembly. Movement of the piston assembly through its compression stroke must thus be accomplished against the pressure of return air in the chamber 29. In order that this opposing pressure may not impede the movement of the piston assembly and lessen its effectiveness, a simple and effective means is provided herein for overcoming such pressure. As shown in Figsf'l and 3 there is formed in the piston rod 24, a longitudinal passage 52 which opens into the chamber 29 above the piston head 21 and communicates through a port 53 with the chamber 28 above the piston head 25. Thus, some of the air in roduced into chamber 28 is permitted to flow through the passage 62 to the upper end of the chamber 29 and acts to balance the pressure of the return air in the lower end of the chamber.

As a result, the unbalanced areas over which the pressure is applied are equivalent to the entire area of the piston head 26 including the area of the piston rod 24. During the compression stroke the air in the lower end of the chamber 29 is forced back through the passageway 34 and into the main air line. The upper end of the chamber 29, being in constant communication with the chamber 28, is also connected to exhaust during the return stroke.

The operator may compress a number of rivets in rapid succession by moving the lever 35 alternately between the partly depressed position shown in Fig. 4 and the fully depressed position of Fig. 3. The engagement of collar 6| with the outer valve 42 gives an indication, which can be felt by the hand, that the lever properly adjusted for the return stroke.

What is claimed is:

1. In a riveting or like machine, the combination of a pair of piston chambers, a pressure fluid operated piston movable within one of said chambers, a second pressure fluid operated piston connected to the first said piston and movable within the other of said chambers, means for controlling the flow of pressure fluid to said chambers including a valve for controlling the flow of pressure fluid to one of said chambers and a valve for controlling the flow of pressure fluid to the other of said chambers, and means for operating said valves, said means acting during a portion of its movement to operate one of said valves and acting during another portion of its movement to operate both of said valves.

2. In a riveting or like machine, the combination of a pair of piston chambers, a pressure fluid operated piston movable within one of said chambers, a pressure fluid operated piston connected to the first said piston and movable within the other of said chambers, means establishing lei ati nwhemeaassmm plants? biive the respective pistons n, ifieaiis for conducting pressurefluid to one of said chambers at a point above the piston therein, means for conducting pressure fluid to the other of said chambers at a point below the piston therein, means for controlling the flow of pressure fluid to said chambers including a valve for controlling the flow of pressure fluid to one of said chambers and a valve for controlling the flow of pressure fluid to the other of said chambers, and means for operating said valves, said means acting during a portion of its movement to operate one of said valves and acting during another portion of its movement to operate both of said valves.

3. In a riveting or like machine, the combination of a pair of piston chambers, a piston assembly comprising a pair of connected piston heads one of which is positioned in one of said chambers and the other of which is positioned in the other of said chambers, a first passageway opening into one of said chambers at a point to drive said piston assembly in one direction, a second passageway opening into the other of said chambers at a point to drive said piston assembly in the opposite direction, a valve for controlling the flow of pressure fluid to said first passageway, a longitudinal passage in said valve communicating with the second said passageway whereby pressure fluid is conducted to the second said passageway, a valve for controlling the flow of pressure fluid through said longitudinal passage, and means for operating said valves, said means being so arranged as to operate only said last mentioned valve during one portion of its movement and to operate both said valves during another portion of its movement.

4. In a device of the class described, the combination of a pair of pressure fluid conducting passageways, a piston type valve for controlling the flow of pressure fluid through one of said passageways and settable to an open and closed position with respect to said one passageway, a longitudinal passage within said valve communieating with the other of the said passageways, a valve for controlling the flow of pressure fluid through said longitudinal passage and settable to an open and closed position with respect to said passage, and means movable to a partly actuated position and a fully actuated position for operating said valves, said means acting in its partly actuated position to set the last; mentioned of said valves to open position and acting in its fully actuated position to set both of said valves to open position.

5. In a device of the class described, the combination of a pair of pressure fluid conducting passageways, a piston type valve for controlling the flow of pressure fluid through one of said passageways and settable to an open and closed position with respect to said one passageway, a longitudinal passage within said valve communicating with the other of the said passageways, a valve for controlling the flow of pressure fluid through said longitudinal passage and settable to an open and closed position with respect to said passage, means movable to a partly actuated position and a fully actuated position for operating said valves, said means acting in its partly actuated position to set the last mentioned of said valves to open position and acting in its fully actuated position to set both of said valves to open position, a yielding means urging the said piston type valve to closed position, and a second yielding means subordinate in strength to the first said yielding means urging the other of said valves to closed position.

6. In a. device of the class described, the combination of a cylindrical bore, means for conducting pressure fluid to one end of said bore, a pair of pressure fluid conducting passageways communicating with said bore, a piston type valve movable within said bore to control the flow of pressure fluid to and from one of said passageways, a longitudinal passage extending throughout the length of said valve and communicating with the other of said passageways, a valve for controlling the flow of pressure fluid through said longitudinal passage, and means for operating said valves, said means being so arranged as to operate only the said last mentioned valve during one portion of its movement and to operate both said valves during another portion of its movement.

7. In a device of the class described, a valve housing, a bushing secured therein and exposed to live pressure fluid at its front end, an outer valve mounted for reciprocation in the bushing and having a shoulder engageable with the bushing to limit rearward movement of the valve, an inner valve mounted for reciprocation in said outer valve and having a shoulder engageable with the outer valve to limit relative rearward movement of the inner valve, resilient means urging both valves rearwardly, the front ends of the valves being exposed constantly to live pressure fluid which thereby assists the resilient means, means for moving first the inner then the outer valve forward, a pair of passages associated with the respective valves and arranged to be supplied with live pressure fluid upon actuation of the associated valve, and means responsive to the actuation of the inner valve to transmit live pressure fluid to t hg rear end 9f the outervalve valve 1n unoperated position.

8. In a device as set forth in claim 7, said resilient means comprising a spring interposed between the inner and the outer valve and a second spring interposed between the outer valve and the housing, said second spring being stronger, or less yieldable, than the first mentioned spring, whereby the operator may alternately operate the inner valve alone and then both valves by applying first a relatively weak and then a stronger pressure on the inner valve.

HOWARD R. FISCHER. 

